This application is based on Japanese Patent Applications No. 2001-109102 filed on Apr. 6, 2001, and No. 2001-220299 filed on Jul. 19, 2001, the disclosure of which is incorporated herein by reference.
The present invention relates to an electromagnetic switch used in a starter for starting an internal combustion engine.
According to an electromagnetic switch in JP-U-63-50432, a sealing member 120 is compressively fitted in a recess 110 formed on the inner wall of a molded cover 100, as shown in FIG. 10. A lead wire 140 of a coil is pulled out of the molded cover 100 through a through hole 130 of the molded cover 100 and a through hole in the sealing member 120. An end of the lead wire 140 pulled out of the molded cover 100 is soldered with a terminal 150 fixed on the molded cover 100. The through hole 130 of the molded cover 100 is sealed with solder 160 in order to secure air-tightness of the molded cover 100. In this electromagnetic switch, the lead wire 140 has to be manually pulled out of the molded cover 100 because the lead wire 140 does not have rigidity. Further, the air-tightness is influenced by a soldering quality.
Incidentally, in this kind of electromagnetic switch, a return spring is slidablly mounted on the outer periphery of a rod supporting a movable contact. However, the return spring is likely to be interfered around the rod when it is mounted onto the rod and when it slides on the rod.
The present invention is made in view of the above problems, and it is an object to provide an electromagnetic switch for a starter, which is capable of being automatically assembled.
It is another object to provide an electromagnetic switch for a starter, which is capable of being automatically assembled and providing air-tightness.
It is further another object to provide an electromagnetic switch for a starter in which a return spring is properly mounted without being interfered.
It is still another object to improve mountability and slidability of the return spring.
According to an aspect of the present invention, in an electromagnetic switch for a starter, a plate-like terminal having rigidity is press-fitted in a bobbin in an axial direction, and an end of an excitation coil wound around the bobbin is connected to the terminal. A cover is mounted such that the terminal passes through the cover.
In this structure, the terminal connected to the excitation coil extends out the molded cover, instead of pulling the excitation coil without having rigidity out of the molded cover. Therefore, steps up to fixing the molded cover can be automatically operated in an assembly process.
According to another aspect of the present invention, a rod supporting a movable contact at an end is movable with a plunger through a return spring in an axial direction. The rod has an annular groove on its outer circumferential surface and a rod cover is fitted on the rod. The rod cover has a flange, a cylindrical part and a distal end opposite to the flange. The cylindrical part has a plurality of projections which project inwardly from the inner circumferential surface of the cylindrical part to be fitted in the annular groove. The plurality of projections is arranged in the circumferential direction. The cylindrical part defines a plurality of slits that extend in the axial direction between the adjacent projections and is closed before the distal end.
In this structure, the cylindrical part other than the distal end of the rod cover can expands radially outward while the plurality of projections is passing on the outer periphery of the rod and before it is fitted in the annular groove when the rod cover is mounted onto the rod. Therefore, the rod cover is properly mounted onto the rod. In addition, since plurality of slits is closed before the distal end and the distal end has an annular shape, the distal end of the cylindrical part is restricted from expanding radially outward so that the cylindrical part remains its original shape after the rod cover is fitted on the rod. The return spring is mounted onto the rod cover by being guided by the outer circumferential surface of the cylindrical part from its distal end side, as a guide surface. Therefore, it is restricted that the return spring is caught in the plurality of slits of the rod cover. Accordingly, the return spring is properly mounted onto and slidable on the rod cover.